Automobile spark-plug.



L. E. JOHNSTON. AUTOMOBILE SPARK PLUG.

APPLICATION FILED MAY l. I9I7.

Patented Sept. 24,1918?.

llelle xllnem LEWIS :EDWARD JOHNSTON, 0F SULLVAN, IVIISSOUR.

AUTOMOBILE SPARK-PLUG.

rescata.

Specication of Letters Patent.

Patented Sept. 24k, Multa.

Application filed May 1, 1917. Serial No. 165,802.

To all whom t may concern:

Be it known that I, Lewis EDWARD JOHN- s'roN, a citizen of the UnitedStates, and a resident of the city of Sullivan, county of Franklin, andState of Missouri, have in-` vented new and useful Improvements 1n ationof the device shall be materially in-y creased. i

One of the great difficulties encounter in the use of spark plugsoninterna-l combustion engines is the short-circuiting of the currentpassing through the plug, this action being due to the fact that theelectrodes become coated with a deposit of carbon, soot, oil or othershort-circuiting material and in time, this accumulation is effective inpreventing the spark plug from performing its intended functions.

l propose to overcome the objection just noted by locating on thecentral electrode of the plug, a disk, theedge or periphery of which'lies immediately adjacent to the inner annular endof the spark plug bodyor shell,l

the same serving as the outer electrode, such construction providing apair of annular edges between which the current may pass at any point toproduce a spark. In other words, my iljfnproved construction providesfor `an annu ar spark gap of considerable circumference, and if thegreater portions of the two edges of the electrodes are coated withcarbon or the like, there will still be suiicient space'on the edges forthe production of the spark, thus enabling the plug to perform itsnormal functions.

One of the objects of my invention is to adjustably mount the disk uponthe central electrode, thereby permitting the spark gap or space betweenthe electrodes to be regulated according to the requirements of theparticular coil-with which the spark plug is employed.

A further objectief my invention is to construct the inner end of thespark plug so as to prevent the accumulation of short-cir cuitingmaterial on the spark points or edges, thereby tending to maintain thesame .in a clean and serviceable condition.

With the foregoing andother objects in view, my invention consists incertain novel features of construction and arrangement of parts,hereinafter more fully described and claimed, and illustrated in theaccompanying drawings, in which- Figure 1 is a side elevational view ofa spark plug constructed in accordance with my invention;

Fig. 2 is a vertical section taken lengthwise through the center of thespark plug with a portion of the insulated core thereof in elevation.

Referring by numerals to the accompanying drawings, which illustrate apractical embodiment of my invention, 10. designates the outer` shell orbody of the plug, the same being formed of metal and providedintermediate its ends with an internally arranged shoulderll. The upperend of this shell or body is internally threaded as designated by 12,and the lower end is externally threaded as designated by 13 in orderthat said body may be screw-seated in the wall of an internal combustionengine.

A core 14 of insulation, preferably porcelain is provided intermediateits ends with an annular rib 15 and when this core is properlypositioned in theshell or body 10, the shoulder on the underside of saidrib bears directly upon a gasket or packing ring 16, which latter restsdirectly upon the shoulder 11.

A gland or packing ring 17 is screwed into the threaded upper end of thebody 10, the lower end of said gland or rin bearing directly upon theshoulder above t e rib 15.

Extending axially through the core la is the central electrode 18, thesame being in the form of a metal rod, both ends of which are threadedand formed on or xed to the lower portion of said rod and'immediately.

above the threaded lower end thereof dis a disk 19 which lits snuglywithin a recess 20 formed in the lower end of core lil.

A portion of the threaded lower end of this electrode extends belowthelower end of the shell or body 10 and screw-seated upon said lowerportion is a disk'l, the top surface of which is preferably flat and theunder-surface being convex. Formed through this dial; is an aperture wl'ch is adapted to receive a suitable tool arxxreby the disk till lill*irc ma be screwed up or down upon the centra electrode to regulatethedistance be tween the edge of said disk and the annular lower edge ofbody 10. The extreme lower end of electrode 18 is pointed as `deshgnatedby-23. The threaded upper portion of electrode 18 is provided with nuts24 and 25 between which the terminal of a conductor may be clamped andinterposed between the nut 24 and the top of core 14 is a packing disk26.

It will be understood that the electriccurrent delivered to the sparkplug by a line connection clamped between the nuts 24 and 25 passesdownward through electrode 18, from thence through disk 21 andin jumpingto the lower edge Vof the cylindrical body 10, produces a spark, therebyigniting the cornpressed charge within the engine cylinder.

The width of the spark gap can readily be regulated by adjusting theposition of disk 2l on the threaded lower portion of electrode 18, thisoperation being accomplished by means of a suitable. tool inserted inthe aperture 22 and rotating said disk 21.

It will 4be noted that the disk 21 forming the central electrode has adiameter `that is equal to or slightly larger than the internal diameterof the lower portion of shell 10 and for this reason any carbon or oilwhich may be thrown onto the convex undersurface of said disk 21 will bedirected outwardly and upwardly and thus be prevented from entering andaccumulating within the chamber between said disk 21 and the lower endof the. porcelain body 14.

It has been demonstrated in practice that there is no tendency of carbonor the like to accumulate on the convex underside of disk 21 and thepointed end 23 of electrode 18, and it is believed that thisself-cleaning action is due to the sweeping or wiping action of thecompressed gases during the tiring ac tion or while under combustion.Further, it has been noted thatthe spark produced by my improved plugwill travel from one `point to another around the annular spark gap, andby virtue of the fact that said spark gap is continuous or in the formof a circle' the plug will continue to perform its tunetions even thoughconsiderable portions of the edge of disk 2l and the lower edge of shell10 bc covered with a coating or deposit of carbon or the like.

For this reason my improved spark plug can be used continuously for amuch greater period of time than a spark' plug having a spark gap formedbetween the attenuated ends of a pair of electrodes.

lit will be readily understood that minor changes in the size, form andconstruction of the various parts of my improved spark Laetrile" plugcan be made and substituted for those herein shown and described,without departing from the spirit of my invention, the scope of which isset forth in the appended claims. A

I claim:

1. The herein described spark plug comprising a substantially tubularbody, a. core of `insulation withinsaid body, the .lower end of whichcore terminates a shortdistance above the lower end ofthe tubular body,a rod passing through the core, the lower portion of which rod isthreaded and projects below the lower end of the tubular body, a nutmounted on the threaded lower end of the rod and occupyingk the recessformed in the lower end of the core, and an electrode in the. form of adisk positioned on the threaded lower end of the rod below thecylindrical body, said disk having a diameter slightly greater than theinternal diameter of the tubular body, andl provided with a fiat topsurface and a smooth'convex lower face, and the end of the rod whichprojects below said disk being pointed.

2. The herein -described spark plug comprising a substantially tubularbody, a core of insulation within said body, the lower" end of whichcore terminates a short distance above the lower end of the tubularbody, a rod lpassing through the core, the lower portion of which rod isthreaded and projects below the lower end of the tubular body, a nutmounted on the threaded lower end of the rod and occupying the recessformed in the lower end of the core, and an electrode in the form of adisk positioned on the threaded lower end of the rod below thecylindrical body, said disk having a di-v ameter slightly greater thanthe internal diameter ot' the tubular body, and said disk having a lflattop surface and a smooth convex lower face and provided with aneccentrically arranged aperture adapted to receive a tool whereby saiddisk can be screwed ondto or from the threaded lower end of said ro 3. Aspark plug having a substantially tubular body, a core of insulationlwithin said tubular body, a rod passing through said core, the lowerportion of said rod being threaded and projecting a substantial distancebelow'the lower end ofthe tubular body, the extreme lower end of saidrod being pointed, and an electrode of disk form screw-seated on thethreaded lower portion of the rod,. the edge of which disk is disposedadjacent to the lower end of the tubular body, and said disk having asmooth convex lowerl face.

LEWIS EDWARD JHNSTUN.

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